Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
vials containing 200 units as powder for reconstitution
Approved indication: Gaucher's disease type I
Patients with Gaucher's disease lack the enzyme glucocerebrosidase. This deficiency results in an accumulation of glucocerebroside which can cause hepatosplenomegaly and bone marrow suppression. A few years ago alglucerase, a modified form of glucocerebrosidase, became available for replacement therapy (see 'New drugs' Aust Prescr 1995;18:7). Imiglucerase is a recombinant form of alglucerase, so it should not have the potential risks of a product derived from pooled human placental tissue.
The two enzymes were compared in a double-blind trial. There were 15 patients in each treatment group. They were given an infusion of 60 U/kg every two weeks for 9 months. At the end of the study there were no significant differences in the effects of treatment on the size of the liver and spleen, the haemoglobin or the platelet count.1
The dose has to be titrated for each individual patient. A small comparative trial found 15 U/kg every two weeks to be as effective as 2.5 U/kg 3 times a week.2 The lower doses may have less effect on the skeletal effects of Gaucher's disease.
Apart from injection site reactions, symptoms suggestive of hypersensitivity have been reported in 4% of patients. These symptoms usually occur during the two-hour infusion. Although 20% of the patients given imiglucerase develop antiglucocerebrosidase antibodies, this is half the frequency seen with alglucerase.1 While the presence of antibodies increases their risk of a hypersensitivity reaction most patients can continue treatment.
There are only about 30 people in Australia being treated with alglucerase, but the annual cost of treatment is approaching $8 million. The launch of imiglucerase should help to reduce the cost per patient.
- Grabowski GA, Barton NW, Pastores G, Dambrosia JM, Banerjee TK, McKee MA, et al. Enzyme therapy in type I Gaucher disease: comparative efficacy of mannose-terminated glucocerebrosidase from natural and recombinant sources. Ann Int Med 1995;122:33-9.
- Zimran A, Elstein D, Levy-Lahad E, Zevin S, Hadas-Halpern I, Bar-Ziv Y, et al. Replacement therapy with imiglucerase for type I Gaucher's disease. Lancet 1995;345:1479-80.